create a new file if doesn't exist

Question

This is my main.cpp:

int main () {
    FILE* file_name;
    file_name= fopen("email1.clear","wb");
return 0;
}

I run it with the ssh (Linux):

g++ main.cpp -o main

but no file has been created. (I must to use: FILE*).

please help.

Your command isn't actually running anything, it's just compiling. You need to run your programm with ./main — SBI, Jan 15 '13 at 11:58
@user1961415: Just `./main`. The program can run by itself and doesn't really need something like an interpreter you would know from e.g. bash, Python, Perl, .. — Benjamin Bannier, Jan 15 '13 at 12:04

score 2 · Answer 1 · answered Jan 15 '13 at 12:02

2

> How Do I Compile/Run My Program?

To compile C/CPP program first.cpp, and create an executable file called first, enter:

$ gcc first.cpp -o first

OR

$ cc first.cpp -o first

To execute program first, enter:

$ ./first

answered Jan 15 '13 at 12:02

Sahal

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Either your C files have an unusual extension or you wrongly use a C compiler to compile C++ code. – Benjamin Bannier Jan 15 '13 at 12:21
@honk, `gcc` is smart enough and runs the C++ frontend when the file extension is `.cpp`. – Hristo Iliev Jan 15 '13 at 14:11
@HristoIliev: Still confusing style. – Benjamin Bannier Jan 15 '13 at 14:15

score 0 · Answer 2 · answered Jul 23 '13 at 04:34

Well I recomend that you use "a+" instead of wb first of all because "a+" let's you create a file if it doesn't exist and if it does it let's you add stuff in the file. Second well I don't know if you are going to use binary because the b in wb is for binary don't put it if you don't need it. So your code should look something like this:

int main () {
    FILE* file_name;
    file_name= fopen("email1.clear","a+");//or just use "w" bot work
return 0;
}

also the file might been placed where the .cpp is save they are usually saved together.

create a new file if doesn't exist

2 Answers2